Weather Banter - Discussion on our upcoming cold spell

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Discussion on our upcoming cold spell

Well, looking at the latest model runs for 01/01/08 GFS has the 200 knot jet
pointing straight at the high pressure which is optimum to collapse it. Low
developing around Newfoundland seems key to jet orientation and things can still
change as orientation is key. Other models have jet backed slightly maintaining
the high more but only a few ensemble members have the jet veered. So, unless
the jet at T+72 changes orientation we are facing the definite possibility of a
mild and zonal January. Still plenty of interest though as the low near
Newfoundland is developing from a relatively data sparse area. I note the 564
DAM line reaches 40N in the western Atlantic and I think that it is this that is
keeping the jet strength going.

COME ON :-)

Will
--

"Will Hand" wrote in message news:...
Very busy ATM with in-laws but I have escaped for a few minutes :-)

OK, first thing, the Russian high circa 1055-1060 mb is not going to disappear
very quickly. It is becoming well established in the models with hints of an
omega block. Some runs like yesterdays GFS break it down very quickly
introducing raging zonality, although this was realistic it is unlikely
because
the breakdown hinged on the orientation of the 200 knot jet coming across the
Atlantic on Friday having the precise orientation to do it, any small change
either way and one of two things happens.

1. Backing - The high stays where it is and a low trundles up to Iceland
putting
us into a rather mild southwesterly with cold air persisting just across North
Sea, this is the recent UKMO scenarios.

2. Veering - The high stays where it is and deep lows crash into the UK
bringing
extensive precipitation and a southeasterly flow on their northern sides,
eventually resulting in a low complex over UK giving a nightmare mix of
rain/sleet/snow but with most snow in the north. ECMWF has been bullish about
this option and is holding its ground. GFS now comes onboard on the 00Z run
31st
but to a lesser extent.

On balance I feel that we are in for an interesting time in January with very
cold air just to our east and lows over the UK - the usual borderline
situation
and a real headache for our professional forecasters.

As I said in a previous post it is highly likely that northern Britain will
bear
the brunt of any disruptive snowfalls, but that all important detail can
change.
A bit more veer in the 200 knot jet and we will have a severe winter situation
with ridging across to Iceland/Greenland and a full blown easterly with
widespread frontal snow. To balance that, a precisely right jet orientation
will
put us into raging zonality for most of January with the high rapidly sliding
away SE.

What an interesting couple of days ahead.

Yes I'm coming :-)

If I don't get another chance to come online I would like to wish everyone a
happy 2008 now!

Will
--

" I shall not commit the fashionable stupidity of regarding everything
I cannot explain as fraud. Carl Jung "

------------------------------------------------------------------------------
-
A COL BH site in East Dartmoor at Haytor, Devon 310m asl (1017 feet).

mailto:
www: http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm

DISCLAIMER - All views and opinions expressed by myself are personal
and do not necessarily represent those of my employer.
------------------------------------------------------------------------------
-

Discussion on our upcoming cold spell

12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to UK
again. We may have to wait till end of tomorrow before evolution for weekend and
beyond becomes clearer. Main emphasis for snow is still in northern Britain.

Will
--

"Will Hand" wrote in message
...
Well, looking at the latest model runs for 01/01/08 GFS has the 200 knot jet
pointing straight at the high pressure which is optimum to collapse it. Low
developing around Newfoundland seems key to jet orientation and things can
still
change as orientation is key. Other models have jet backed slightly
maintaining
the high more but only a few ensemble members have the jet veered. So, unless
the jet at T+72 changes orientation we are facing the definite possibility of
a
mild and zonal January. Still plenty of interest though as the low near
Newfoundland is developing from a relatively data sparse area. I note the 564
DAM line reaches 40N in the western Atlantic and I think that it is this that
is
keeping the jet strength going.

COME ON :-)

Will
--

"Will Hand" wrote in message news:...
Very busy ATM with in-laws but I have escaped for a few minutes :-)

OK, first thing, the Russian high circa 1055-1060 mb is not going to
disappear
very quickly. It is becoming well established in the models with hints of an
omega block. Some runs like yesterdays GFS break it down very quickly
introducing raging zonality, although this was realistic it is unlikely
because
the breakdown hinged on the orientation of the 200 knot jet coming across
the
Atlantic on Friday having the precise orientation to do it, any small change
either way and one of two things happens.

1. Backing - The high stays where it is and a low trundles up to Iceland
putting
us into a rather mild southwesterly with cold air persisting just across
North
Sea, this is the recent UKMO scenarios.

2. Veering - The high stays where it is and deep lows crash into the UK
bringing
extensive precipitation and a southeasterly flow on their northern sides,
eventually resulting in a low complex over UK giving a nightmare mix of
rain/sleet/snow but with most snow in the north. ECMWF has been bullish
about
this option and is holding its ground. GFS now comes onboard on the 00Z run
31st
but to a lesser extent.

On balance I feel that we are in for an interesting time in January with
very
cold air just to our east and lows over the UK - the usual borderline
situation
and a real headache for our professional forecasters.

As I said in a previous post it is highly likely that northern Britain will
bear
the brunt of any disruptive snowfalls, but that all important detail can
change.
A bit more veer in the 200 knot jet and we will have a severe winter
situation
with ridging across to Iceland/Greenland and a full blown easterly with
widespread frontal snow. To balance that, a precisely right jet orientation
will
put us into raging zonality for most of January with the high rapidly
sliding
away SE.

What an interesting couple of days ahead.

Yes I'm coming :-)

If I don't get another chance to come online I would like to wish everyone a
happy 2008 now!

Will
--

" I shall not commit the fashionable stupidity of regarding everything
I cannot explain as fraud. Carl Jung "

------------------------------------------------------------------------------
-
A COL BH site in East Dartmoor at Haytor, Devon 310m asl (1017 feet).

mailto:
www:
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm

DISCLAIMER - All views and opinions expressed by myself are personal
and do not necessarily represent those of my employer.

------------------------------------------------------------------------------
-

Discussion on our upcoming cold spell

Will Hand wrote:
12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to UK
again. We may have to wait till end of tomorrow before evolution for weekend and
beyond becomes clearer. Main emphasis for snow is still in northern Britain.

Will
--

Where can I find the link to the ECMWF 'Jet' maps?

Thanks

--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net

Discussion on our upcoming cold spell

"Keith (Southend)" wrote in message
...
Will Hand wrote:
12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to UK
again. We may have to wait till end of tomorrow before evolution for weekend
and
beyond becomes clearer. Main emphasis for snow is still in northern Britain.

Will
--

Where can I find the link to the ECMWF 'Jet' maps?

Thanks

I estimated the jet from 850, 500 and MSLP maps on Wetterzentrale.

Will
--

Discussion on our upcoming cold spell

On 1 Jan, 19:15, "Will Hand" wrote:
12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to UK
again. We may have to wait till end of tomorrow before evolution for weekend and
beyond becomes clearer. Main emphasis for snow is still in northern Britain.

Will
--

For someone who was my college lecturer, at one stage, you are
displaying an extreme "sit on the fence" opinion, which would have
been ridiculed had your 'pupils' done the same on that course.

I might prefer the 200mb low, which is appearently too high for winter
jet stream analysis, but 25 years worth of study has served me very
well.

I'm afraid, desperately searching for a model product that fits what
you want to happen, does not always indicate a reliable forecast.

Discussion on our upcoming cold spell

On 1 Jan, 21:20, "Will Hand" wrote:
wrote in message

...

On 1 Jan, 19:15, "Will Hand" wrote:
12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to UK
again. We may have to wait till end of tomorrow before evolution for weekend
and
beyond becomes clearer. Main emphasis for snow is still in northern Britain.

Will
--

For someone who was my college lecturer, at one stage, you are
displaying an extreme "sit on the fence" opinion, which would have
been ridiculed had your 'pupils' done the same on that course.

That's science for you.

I might prefer the 200mb low, which is appearently too high for winter
jet stream analysis, but 25 years worth of study has served me very
well.

200 mb is in the stratosphere in polar latitudes as you well know (or at least
ought to!).

Not always, as you well know (or should do).

I challenge you to give me an example of where the 200mb and 300mb
streamlines differ at a statisically siginficant level on the current
forecast charts, especially over western Europe.

Discussion on our upcoming cold spell

wrote in message
...
On 1 Jan, 19:15, "Will Hand" wrote:
12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to UK
again. We may have to wait till end of tomorrow before evolution for weekend
and
beyond becomes clearer. Main emphasis for snow is still in northern Britain.

Will
--

For someone who was my college lecturer, at one stage, you are
displaying an extreme "sit on the fence" opinion, which would have
been ridiculed had your 'pupils' done the same on that course.

I might prefer the 200mb low, which is appearently too high for winter
jet stream analysis, but 25 years worth of study has served me very
well.

I'm afraid, desperately searching for a model product that fits what
you want to happen, does not always indicate a reliable forecast.

I could have mentioned the 12Z 1/1/08 JMA run but I didn't. This run shows the
uncertainty at present. I have the luxury of not having to make a decision,
unlike operational forecasters, which you were once. Surely you appreciate how
finely balanced the situation is, I have tried to be helpful to others on here
to highlight the key cause of that uncertainty in my view (which might be wrong
of course). If you really want options then I'll give you some for next week:

1. Severe winter scenario with raging easterly and high pressure Scandinavia -
Greenland 5%
2. Mild zonality with lows tracking to Iceland to Scandinavia 40%
3. Colder with deep lows running into UK with cold air over Northern Britain 55%

Right, you come off the fence with that lot!

Will
--

Discussion on our upcoming cold spell

wrote in message
...
On 1 Jan, 21:20, "Will Hand" wrote:
wrote in message

...

On 1 Jan, 19:15, "Will Hand" wrote:
12Z runs, particularly ECMWF, have jet more veered and the difference in
evolution is quite dramatic. Lows further south and pushing closer in to
UK
again. We may have to wait till end of tomorrow before evolution for
weekend
and
beyond becomes clearer. Main emphasis for snow is still in northern
Britain.

Will
--

For someone who was my college lecturer, at one stage, you are
displaying an extreme "sit on the fence" opinion, which would have
been ridiculed had your 'pupils' done the same on that course.

That's science for you.

Deliberately lowering someones course marks because you dont like
their attitude was never science.

What??????
I'm not sure I like where this may be leading John, I suggest you e-mail me
because I will not discuss professional matters in public and neither should
you.

Will
--